Fruits 20 Palm oil 19 Empty fruit bunches 12 Oil palm empty fruit bunch 12 Elaeis 11 Biomass 8 Empty fruit bunch 8 Oil palm biomass 7 Biochar 6 Oil palm empty fruit bunch (OPEFB) 6 Charcoal 5 Article 4 Cellulose 4 Fourier transform infrared spectroscopy 4 Pre-treatment 4 Thermogravimetric analysis 4 empty fruit bunch 4 Agricultural robots 3 Agricultural wastes 3 Bio chars 3 Biogas 3 Calorific value 3 Carbonization 3 Carboxymethyl cellulose 3 Heating value 3 Mechanical properties 3 Oil palm empty fruit bunches 3 Pyrolysis 3 Scanning electron microscopy 3 Self-sustained carbonization 3